I hope this is the right place... if not, my apologies. I've done quite a bit of reading, but just wanted a little more input from people who know what they're doing.
I haven't had my own tank for very long, and am still doing my best to learn how to keep my fish their happiest and healthiest. I would love to put some live plants into my tank-- a 20 gallon, which currently has only logs and tacky fake plants. My tank is made up mostly of cory cats-- I seem to have fallen in love with the silly little buggers. I also have 2 plecos and a few assorted live-bearers.
What sorts of plants would you recommend? From what I've seen, cories don't seem to be too picky about, well, anything... but are there any plants that they might particularly like over others?
I've also got a few sand questions. Right now, the bottom of my tank has blue gravel. My parents (who have worked with fish for 20+ years in the wholesale business) insist that they have never had trouble with cories on gravel in the past and that changing over to sand would be messy, wasteful, and unnecessary. The cories don't seem to mind it too much, either. However, I have read that sand is much better for them and their barbels.
So, I have decided that I want to switch over to sand or something similar, but I really don't know what to expect. I imagine I'm going to have to, essentially, start my tank all over again? Is this something that is going to require my fish being relocated for more than a couple of hours? I don't really have any place suitable to keep them for very long, and I don't want to stress them out too badly.
Also, is there a particular type of sand that would be best? Is color important? I like bright colors, but would my scaled-friends prefer something a little more natural? Are there any potential issues that I can/should prepare for?
Sorry if my questions seem silly. We've all got to learn somehow, right?

Thanks!